Paleontologists recently celebrated National Fossil Day, a day to educate populations about the scientific value of the study of fossils and the importance of preserving them for future generations. The nation recognizes National Fossil Day during Earth Science Week in October every year to promote public awareness of historic remains. Fossil discovery is not uncommon to Illinois. In fact, Illinois has recognized one particular fossil for being a unique state treasure.

The Tully monster, Illinois’ state fossil, was a soft-bodied marine animal. It had no shell and no backbone, and it lived in the ocean. When the land that is now Illinois was covered in dense swamps and forestry, the Tully monster is said to have swam through the shallow seas of western and central Illinois. The way the Tully monster was preserved is one of its unique factors. Typically fossils only contain the hard external shell of animals that have been trapped under layers of mud and organic matter. The soft flesh of animals decays quickly, and it likely serves as food for scavengers. The anatomy of the Tully monster, however, has been well preserved due to chemical reactions that created a hardened exterior around the buried body. The conditions for fossilization in the land’s mineral sites were just right for an extraordinary discovery that would happen eons later.

Another unique characteristic of the Tully monster is that the Tully monster is found nowhere else in the world! The Tully monster’s remains were discovered in the 1850s by Francis Tully, a fossil collector who brought his find to paleontologists at the Field Museum of Natural History in Chicago. Unable to identify the remains, the Tully monster became an unusual specimen. After years of research, scientists concluded that the Tully monster had no close relation to any known animal, living or extinct. Though it is commonly found in the state, the Tully monster is in a category of its own.

National Fossil Day allows people of all ages to share their experiences and knowledge about fossils and prehistoric life. Discoveries like the Tully monster help foster a greater appreciation for the work of paleontologists. They also highlight the uniqueness of Illinois. Though a number of states have declared state fossils, none are quite like the Tully monster.